Genetics definitely play a part but doesn't hurt to moisturize. I used Mama Mio and now I'm using Mambino Organics belly butter--love the smell of it. My stretch marks didn't happen til late 3rd trimester so yes at first I was gutted, but now have resigned to the fact that this bubba is just much bigger than my first and my belly just has grown outwards big time! I haven't gained that much weight and didn't get any marks in my first pregnancy. Part of being a mummy and glad they do fade. The itching has started later too and I just rub more belly butter to help with it.